The Travellers are engaged by an Aslan lord to rescue his missing son Ftahteas from the world of Thebus. Ftahteas has fallen victim to local conditions and is in grave distress, not least since he is being hunted by Aslan-hating humans who intend to claim they mistook Ftahteas and his followers for local wildlife. The rescue attempt leads the Travellers to one of the old cities of Thebus, bombed but not quite destroyed in the last days of the Sindalian Empire. The biggest obstacle to the rescue, however, is Ftahteas himself.

Lions of Thebus expands one of the Patron encounters in the Pirates of Drinax campaign into a full adventure, though it can be used in any Traveller campaign.